Lubricant composition based on fatty triamines

ABSTRACT

A lubricant composition includes at least one base oil, at least one organomolybdenum compound, at least one compound including a dithiophosphate group and at least one fatty triamine. The lubricant composition has good friction properties for both steel/steel contacts and steel/carbon coating contacts, as well as for carbon coating/carbon coating contacts, whilst retaining good anti-wear properties.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Phase Entry of International PatentApplication No. PCT/EP2014/077942, filed on Dec. 16, 2014, which claimspriority to French Patent Application Ser. No. 13 62 843, filed on Dec.17, 2013, both of which are incorporated by reference herein.

TECHNICAL FIELD

The present invention is applicable to the field of lubricants, inparticular lubricants for engines, and more particularly for motorvehicle engines. More particularly, the present invention relates to alubricant composition comprising at least one base oil, at least oneorganomolybdenum compound, at least one compound comprising adithiophosphate group and at least one fatty triamine. The lubricantcomposition according to the invention has good friction properties forboth steel/steel contacts, and steel/carbon coating contacts as well asfor carbon coating/carbon coating contacts, whilst retaining goodanti-wear properties.

The present invention also relates to a lubrication process utilizingthis composition. The present invention also relates to a process forreducing friction between two steel surfaces, in particular in anengine, and more particularly in a motor vehicle engine. The presentinvention also relates to a process for reducing friction between asteel surface and a carbon-covered surface, in particular in an engine,and more particularly in a motor vehicle engine. The present inventionalso relates to a process for reducing friction between twocarbon-covered surfaces, and more particularly in a motor vehicleengine.

The present invention also relates to a process for reducing the fuelconsumption of a vehicle, and more particularly of a motor vehicle. Thepresent invention also relates to the use of a fatty triamine in alubricant composition for reducing friction between two steel surfaces,in particular in an engine, and more particularly in a motor vehicleengine. The present invention also relates to the use of a fattytriamine in a lubricant composition for reducing friction between asteel surface and a carbon-covered surface, in particular in an engine,and more particularly in a motor vehicle engine.

The present invention also relates to the use of a fatty triamine in alubricant composition for reducing friction between two carbon-coveredsurfaces, in particular in an engine, and more particularly in a motorvehicle engine. The present invention also relates to the use of a fattytriamine in a lubricant composition for reducing the fuel consumption ofa vehicle, and more particularly of a motor vehicle. The presentinvention also relates to a composition of the additives concentratetype comprising at least one organomolybdenum compound, at least onecompound comprising a dithiophosphate group and at least one fattytriamine.

BACKGROUND

The objective of lubricants is to reduce the phenomena of friction andwear of the mechanical parts, in particular in vehicle engines, and moreparticularly in motor vehicle engines. In order to reduce these frictionphenomena, it is known to incorporate friction modifiers into thelubricants. Among the friction modifiers, the organomolybdenum compoundsrepresent a family of compounds, the friction phenomenon reductionproperties of which have been broadly described, and more particularlywith respect to contacts between two steel surfaces. However, it isknown to a person skilled in the art that the use of organomolybdenumcompounds, in particular of organomolybdenum compounds comprising adithiocarbamate group, can cause worsening of the phenomena of wear ofmechanical parts. Thus, in order to solve this problem, the combinationof an organomolybdenum compound and an anti-wear compound such as acompound comprising a dithiophosphate group in a lubricant compositionhas been broadly described.

The document U.S. Pat. No. 5,650,381 describes in particular a lubricantcomposition comprising an organomolybdenum compound and a zincdithiophosphate. Moreover, it is known to apply a coating to parts, inparticular metal parts, making it possible to increase their wearresistance under conditions of intensive and repeated friction. Amongthe existing technologies, carbon coatings are known, and in particularDLC (Diamond Like Carbon) coatings based on an amorphous carbon materialwith properties close to those of diamond.

Thus, the DLC coatings are used as coatings of the surfaces of vehicleengine parts, and in particular motor vehicle engine parts. However, itis also known that the properties of reduction of the friction phenomenaof a carbon coating, and in particular of a DLC coating, can be altered,or even degraded in the presence of a lubricant. More particularly, ithas been observed that the organomolybdenum compounds present in alubricant can cause a carbon coating present on a surface to becomedegraded or even to peel off, and this degradation can be exacerbated asthe organomolybdenum compounds content in the lubricant increases. Thus,research has been carried out into lubricants that are compatible withsurfaces covered with a carbon material, and in particular a DLC coatingor a nanodiamond coating, these lubricants comprising noorganomolybdenum compounds.

For example, the document EP 2479247 describes a lubricant comprising acompound based on a zinc phosphate compound and a sulphur-containingcompound. Moreover, the document EP 1338641 describes a lubricantcomprising an amine as friction modifier compatible with a surfacehaving a DLC coating. However, this document gives no teaching about thefriction phenomena reduction properties of these lubricants forsteel/steel contacts. Furthermore, this document gives no teaching aboutthe anti-wear properties of these lubricants, either for steel/steel orsteel/carbon coating contacts. As the use of carbon coating in engines,in particular of motor vehicles is growing, there is therefore still aneed for research into lubricants having both good friction propertiesfor steel/steel contacts, for steel/carbon coating contacts and forcarbon coating/carbon coating contacts, whilst retaining good anti-wearproperties.

An objective of the present invention is to provide a lubricantcomposition overcoming some or all of the abovementioned drawbacks.Another objective of the invention is to provide a lubricant compositionthe formulation of which is easy to implement. Another objective of thepresent invention is to provide a lubrication process for reducingfriction between two steel surfaces, between a steel surface and acarbon-covered surface as well as between two carbon-covered surfaces.

SUMMARY

An object of the invention is therefore a lubricant compositioncomprising:

at least one base oil,

at least one organomolybdenum compound,

at least one compound comprising a dithiophosphate group, and

at least one fatty triamine.

Surprisingly, the applicant has found that the presence of at least oneorganomolybdenum compound, at least one compound comprising adithiophosphate group and at least one fatty triamine in a lubricantcomposition makes it possible to give the lubricant composition goodfriction properties for steel/steel contacts, steel/carbon coatingcontacts and carbon coating/carbon coating contacts simultaneously.Thus, the present invention makes it possible to formulate lubricantcompositions comprising an optimized organomolybdenum compound contentand having good friction properties for steel/steel contacts andsteel/carbon coating contacts as well as for carbon coating/carboncoating contacts.

Advantageously, the lubricant compositions according to the inventionhave good friction properties for steel/steel contacts, steel/carboncoating contacts and carbon coating/carbon coating contacts, whilstretaining good anti-wear properties. Advantageously, the lubricantcompositions according to the invention allow fuel savings in all theoperating phases of a vehicle engine, preferentially a motor vehicleengine, and more particularly when starting. Advantageously, thelubricant compositions according to the invention have good storagestability as well as a viscosity that varies very little or not at all.

In an embodiment of the invention, the lubricant composition essentiallyconsists of:

at least one base oil,

at least one organomolybdenum compound,

at least one compound comprising a dithiophosphate group, and

at least one fatty triamine.

The invention also relates to an engine oil comprising a lubricantcomposition as defined above. The invention also relates to the use of alubricant composition as defined above for the lubrication of mechanicalparts, in particular in transmissions and/or vehicle engines,preferentially motor vehicle engines. The invention also relates to theuse of a lubricant composition as defined above for reducing frictionbetween two steel surfaces, in particular in a vehicle engine,preferentially a motor vehicle engine.

The invention also relates to the use of an abovementioned lubricantcomposition for reducing friction between a steel surface and acarbon-covered surface, in particular in a vehicle engine,preferentially a motor vehicle engine. The invention also relates to theuse of a lubricant composition as defined above for reducing frictionbetween two carbon-covered surfaces, in particular in a vehicle engine,preferentially a motor vehicle engine. The invention also relates to theuse of a lubricant composition as defined above for reducing the fuelconsumption of vehicles, preferentially of motor vehicles.

The invention also relates to a process for the lubrication ofmechanical parts, in particular in transmissions and/or vehicle engines,preferentially motor vehicle engines, comprising at least one step ofbringing at least one part into contact with a lubricant composition asdefined above. The invention also relates to a process for reducingfriction between two steel surfaces, in particular in a vehicle engine,preferentially a motor vehicle engine, comprising at least one step ofbringing at least one of the steel surfaces into contact with alubricant composition as defined above. The invention also relates to aprocess for reducing friction between a steel surface and acarbon-covered surface, in particular in a vehicle engine,preferentially a motor vehicle engine, comprising at least one step ofbringing at least one of the surfaces into contact with a lubricantcomposition as defined above. The invention also relates to a processfor reducing friction between two carbon-covered surfaces, in particularin a vehicle engine, preferentially a motor vehicle engine, comprisingat least one step of bringing at least one of the carbon-coveredsurfaces into contact with a lubricant composition as defined above. Theinvention also relates to a process for reducing the fuel consumption ofa vehicle, preferentially of a motor vehicle, comprising at least onestep of bringing a mechanical part of the vehicle engine into contactwith a lubricant composition as defined above.

The invention also relates to the use of a fatty triamine in a lubricantcomposition comprising at least one base oil, at least oneorganomolybdenum compound and at least one compound comprising adithiophosphate group for reducing friction between two steel surfaces,in particular in a vehicle engine, preferentially a motor vehicleengine. The invention also relates to the use of a fatty triamine in alubricant composition comprising at least one base oil, at least oneorganomolybdenum compound and at least one compound comprising adithiophosphate group for reducing friction between a steel surface anda carbon-covered surface, in particular in a vehicle engine,preferentially a motor vehicle engine. The invention also relates to theuse of a fatty triamine in a lubricant composition comprising at leastone base oil, at least one organomolybdenum compound and at least onecompound comprising a dithiophosphate group for reducing frictionbetween two carbon-covered surfaces, in particular in a vehicle engine,preferentially a motor vehicle engine. The invention also relates to theuse of a fatty triamine in a lubricant composition comprising at leastone base oil, at least one organomolybdenum compound and at least onecompound comprising a dithiophosphate group for reducing the fuelconsumption of a vehicle, preferentially of a motor vehicle.

The invention also relates to a composition of the additives concentratetype comprising:

at least one organomolybdenum compound,

at least one compound comprising a dithiophosphate group, and

at least one fatty triamine.

DETAILED DESCRIPTION

The percentages given below correspond to percentages by mass of activeingredient.

Organomolybdenum Compound

The lubricant composition according to the invention comprises at leastone organomolybdenum compound. By organomolybdenum compound according tothe invention, is meant any oil-soluble organomolybdenum compound. In anembodiment of the invention, the organomolybdenum compound can beselected from the organic molybdenum complexes such as the molybdenumcarboxylates, esters, amides, which can be obtained by reaction ofmolybdenum oxide or of ammonium molybdates with fats, glycerides, fattyacids or fatty acid derivatives (esters, amines, amides etc.).

In a preferred embodiment of the invention, the organomolybdenumcompound is selected from the molybdenum complexes that are free ofsulphur and of phosphorus, with amide-type ligands, mainly prepared bythe reaction of a source of molybdenum, which can be for exampletrimolybdenum oxide, and an amine derivative, and fatty acids comprisingfor example from 4 to 28 carbon atoms, preferentially from 8 to 18carbon atoms, such as for example the fatty acids contained in animal orvegetable oils. The synthesis of such compounds is for example describedin the patents U.S. Pat. No. 4,889,647, EP 0546357, U.S. Pat. No.5,412,130, EP 1770153.

In a preferred embodiment of the invention, the organomolybdenumcompound is selected from the organic molybdenum complexes obtained bythe reaction:

-   -   (i) of a mono-, di- or triglyceride-type fat, or fatty acid,    -   (ii) of an amine source of formula (A):

-   -   in which:        -   X¹ represents an oxygen atom or a nitrogen atom,        -   X² represents an oxygen atom or a nitrogen atom,        -   n and m represent 1 when X¹ or X² represent an oxygen atom,        -   n and m represent 2 when X¹ or X² represent a nitrogen atom,    -   (iii) and of a source of molybdenum selected from trimolybdenum        oxide or the molybdates, preferentially ammonium molybdate, in a        quantity sufficient to provide 0.1 to 30% of molybdenum with        respect to the total weight of complex.

In an embodiment of the invention, the organic molybdenum complex cancomprise from 2 to 8.5% by weight of molybdenum with respect to theweight of the complex.

In a preferred embodiment of the invention, the organic molybdenumcomplex is constituted by at least one of the compounds of formula (I)or (II), alone or in a mixture:

-   -   in which:        -   X¹ represents an oxygen atom or a nitrogen atom;        -   X² represents an oxygen atom or a nitrogen atom;        -   n represents 1 when X¹ represents an oxygen atom and m            represents 1 when X² represents an oxygen atom;        -   n represents 2 when X¹ represents a nitrogen atom and m            represents 2 when X² represents a nitrogen atom;        -   R₁ represents a linear or branched, saturated or unsaturated            alkyl group, comprising from 3 to 30 carbon atoms,            preferentially from 3 to 20 carbon atoms, advantageously            from 7 to 17 carbon atoms;

-   -   in which:        -   X¹ represents an oxygen atom or a nitrogen atom;        -   X² represents an oxygen atom or a nitrogen atom;        -   n represents 1 when X¹ represents an oxygen atom and m            represents 1 when X² represents an oxygen atom;        -   n represents 2 when X¹ represents a nitrogen atom and m            represents 2 when X² represents a nitrogen atom;        -   R₁ represents a linear or branched, saturated or unsaturated            alkyl group, comprising from 3 to 30 carbon atoms,            preferentially from 3 to 20 carbon atoms, advantageously            from 7 to 17 carbon atoms;

R₂ represents a linear or branched, saturated or unsaturated alkylgroup, comprising from 3 to 30 carbon atoms, preferentially from 3 to 20carbon atoms, advantageously from 7 to 17 carbon atoms.

In an embodiment of the invention, the organic molybdenum complex isprepared by the reaction:

-   -   (i) of a mono-, di- or triglyceride-type fat, or fatty acid,    -   (ii) of diethanolamine or 2-(2-aminoethyl) aminoethanol,    -   (iii) and of a source of molybdenum selected from trimolybdenum        oxide or the molybdates, preferentially ammonium molybdate, in a        quantity sufficient to provide 0.1 to 20.0% of molybdenum with        respect to the weight of complex.

In a preferred embodiment of the invention, the organic molybdenumcomplex is constituted by at least one compound of formula (I-a) or(II-a), alone or in a mixture:

in which R₁ represents a linear or branched, saturated or unsaturatedalkyl group, comprising from 3 to 30 carbon atoms, preferentially from 3to 20 carbon atoms, advantageously from 7 to 17 carbon atoms,

in which R₁ represents a linear or branched, saturated or unsaturatedalkyl group, comprising from 3 to 30 carbon atoms, preferentially from 3to 20 carbon atoms, advantageously from 7 to 17 carbon atoms.

In another embodiment, the organomolybdenum compound can be selectedfrom the molybdenum dithiophosphates or molybdenum dithiocarbamates. Ina preferred embodiment of the invention, the organomolybdenum compoundis selected from the molybdenum dithiocarbamates. The molybdenumdithiocarbamate compounds (Mo-DTC compounds) are complexes formed by ametal core linked to one or more ligands, the ligand being adithiocarbamate group of alkyls. These compounds are well known to aperson skilled in the art.

In an embodiment of the invention, the Mo-DTC compound can comprise from1 to 40%, preferably from 2 to 30%, more preferentially from 3 to 28%,advantageously from 4 to 15% by mass of molybdenum, with respect to thetotal mass of Mo-DTC compound. In another embodiment of the invention,the Mo-DTC compound can comprise from 1 to 40%, preferably from 2 to30%, more preferentially from 3 to 28%, advantageously from 4 to 15% bymass of sulphur, with respect to the total mass of Mo-DTC compound. Inanother embodiment of the invention, the Mo-DTC compound can be selectedfrom those the core of which has two molybdenum atoms (also calleddimeric Mo-DTC) and those the core of which present three molybdenumatoms (also called trimeric Mo-DTC).

In another embodiment of the invention, the trimeric Mo-DTC compoundscorrespond to the formula Mo3SkLn in which:

-   -   k represents an integer at least equal to 4, preferably ranging        from 4 to 10, advantageously from 4 to 7,    -   n is an integer ranging from 1 to 4, and    -   L is a dithiocarbamate group of alkyls comprising from 1 to 100        carbon atoms, preferably from 1 to 40 carbon atoms,        advantageously from 3 to 20 carbon atoms.

As examples of trimeric Mo-DTC compounds according to the invention, thecompounds and their preparation processes as described in the documentsWO 98/26030 and U.S. Pat. No. 2003/022954 may be mentioned. In apreferred embodiment of the invention, the Mo-DTC compound is a dimericMo-DTC compound. As examples of dimeric Mo-DTC compounds, the compoundsand their preparation processes as described in the documents EP0757093, EP 0719851, EP 0743354 or EP 1013749 may be mentioned.

The dimeric Mo-DTC compounds correspond generally to the compounds offormula (III):

in which:

-   -   R₃, R₄, R₅, R₆, identical or different, represent independently        a hydrocarbon group selected from the alkyl, alkenyl, aryl,        cycloalkyl or cycloalkenyl groups,    -   X₃, X₄, X₅ and X₆, identical or different, represent        independently an oxygen atom or a sulphur atom.

By alkyl group within the meaning of the invention, is meant a linear orbranched, saturated or unsaturated hydrocarbon-containing group,comprising from 1 to 24 carbon atoms. In an embodiment of the invention,the alkyl group is selected from the group formed by methyl, ethyl,propyl, isopropyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, iso-pentyl,neopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl,tridecyl, isotridecyl, tetradecyl, hexadecyl, stearyl, icosyl, docosyl ,tetracosyl, triacontyl, 2-ethylhexyl, 2-butyloctyl, 2-butyldecyl,2-hexyloctyl, 2-hexyldecyl, 2-octyldecyl, 2-hexyldodecyl,2-octyldodecyl, 2-decyltetradecyl, 2-dodecylhexadecyl,2-hexadecyloctadecyl, 2-tetradecyloctadecyl, myristyl, palmityl andstearyl. By alkenyl group within the meaning of the present invention,is meant a linear or branched hydrocarbon-containing group comprising atleast one double bond and comprising from 2 to 24 carbon atoms. Thealkenyl group can be selected from vinyl, allyl, propenyl, butenyl,isobutenyl, pentenyl, isopentenyl, hexenyl, heptenyl, octenyl, nonenyl,decenyl, undecenyl, dodecenyl, tetradecenyl and oleic.

By aryl group within the meaning of the present invention, is meant apolycyclic aromatic hydrocarbon or an aromatic group, substituted or notsubstituted with an alkyl group. The aryl group can comprise from 6 to24 carbon atoms. In an embodiment, the aryl group can be selected fromthe group formed by phenyl, toluyl, xylyl, cumenyl, mesityl, benzyl,phenethyl, styryl, cinnamyl, benzhydryl, trityl, ethylphenyl,propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl,octylphenyl, nonylphenyl, decylphenyl, undecylphenyl, dodecylphenyl,phenylphenyl, benzylphenyl, phenyl-styrene, p-cumylphenyl and naphthyl.Within the meaning of the present invention, the cycloalkyl groups andthe cycloalkenyl groups can be selected, non-limitatively, from thegroup constituted by cyclopentyl, cyclohexyl, cycloheptyl,methylcyclopentyl, methylcyclohexyl, methylcycloheptyl, cyclopentenyl,cyclohexenyl, cycloheptenyl, methylcyclopentenyl, methylcyclohexenyl.The cycloalkyl groups and the cycloalkenyl groups can comprise from 3 to24 carbon atoms.

In a preferred embodiment of the invention, R₃, R₄, R₅ and R₆, identicalor different, represent independently an alkyl group comprising from 4to 18 carbon atoms or an alkenyl group comprising from 2 to 24 carbonatoms. In an embodiment of the invention, X₃, X₄, X₅ and X₆ can beidentical and can represent a sulphur atom. In another embodiment of theinvention, X₃, X₄, X₅ and X₆ can be identical and can be an oxygen atom.In another embodiment of the invention, X₃ and X₄ can represent asulphur atom and X₅ and X₆ can represent an oxygen atom. In anotherembodiment of the invention, X₃ and X₄ can represent an oxygen atom andX₅ and X₆ can represent a sulphur atom.

In another embodiment of the invention; the ratio of the number ofsulphur atoms to the number of oxygen atoms (S/O) of the Mo-DTC compoundcan vary from (1/3) to (3/1). In another embodiment of the invention,the Mo-DTC compound of formula (A) can be selected from a symmetricalMo-DTC compound, an asymmetrical Mo-DTC compound and a combinationthereof. By symmetrical Mo-DTC compound according to the invention, ismeant an Mo-DTC compound of formula (III) in which the R₃, R₄, R₅ and R₆groups are identical. By asymmetrical Mo-DTC compound according to theinvention, is meant an Mo-DTC compound of formula (III) in which the R₃and R₄ groups are identical, the R₅ and R₆ groups are identical and theR₃ and R₄ groups are different from the R₅ and R₆ groups. In a preferredembodiment of the invention, the Mo-DTC compound is a mixture of atleast one symmetrical Mo-DTC compound and at least one asymmetricalMo-DTC compound.

In an embodiment of the invention, R₃ and R₄, which are identical,represent an alkyl group comprising from 5 to 15 carbon atoms and R₅ andR₆, which are identical and different from R₃ and R₄, represent an alkylgroup comprising from 5 to 15 carbon atoms. In a preferred embodiment ofthe invention, R₃ and R₄, which are identical, represent an alkyl groupcomprising from 6 to 10 carbon atoms and R₅ and R₆ represent an alkylgroup comprising from 10 to 15 carbon atoms. In another preferredembodiment of the invention, R₃ and R₄, which are identical, representan alkyl group comprising from 10 to 15 carbon atoms and R₅ and R₆represent an alkyl group comprising from 6 to 10 carbon atoms. Inanother preferred embodiment of the invention, R₃, R₄, R₅ and R₆, whichare identical, represent an alkyl group comprising from 5 to 15 carbonatoms, preferably from 8 to 13 carbon atoms.

Advantageously, the Mo-DTC compound is selected from the compounds offormula (Ill) in which:

-   X₃ and X₄ represent an oxygen atom,-   X₅ and X₆ represent a sulphur atom,-   R₃ represents an alkyl group comprising 8 carbon atoms or an alkyl    group comprising 13 carbon atoms,-   R₄ represents an alkyl group comprising 8 carbon atoms or an alkyl    group comprising 13 carbon atoms,-   R₅ represents an alkyl group comprising 8 carbon atoms or an alkyl    group comprising 13 carbon atoms,-   R₆ represents an alkyl group comprising 8 carbon atoms or an alkyl    group comprising 13 carbon atoms.

Thus, advantageously, the Mo-DTC compound is selected from the compoundsof formula (III-a)

in which the R₃, R₄, R₅ and R₆ groups are as defined for formula (III).

More advantageously, the Mo-DTC compound is a mixture of:

-   an Mo-DTC compound of formula (III-a) in which R₃, R₄, R₅ and R₆    represent an alkyl group comprising 8 carbon atoms,-   an Mo-DTC compound of formula (III-a) in which R₃, R₄, R₅ and R₆    represent an alkyl group comprising 13 carbon atoms, and-   an Mo-DTC compound of formula (III-a) in which R₃ and R₄ represent    an alkyl group comprising 13 carbon atoms and R₅ and R₆ represent an    alkyl group comprising 8 carbon atoms, and/or-   an Mo-DTC compound of formula (A1) in which R₃ and R₄ represent an    alkyl group comprising 8 carbon atoms and R₅ and R₆ represent an    alkyl group comprising 13 carbon atoms.

As examples of Mo-DTC compounds, the products Molyvan L, Molyvan 807 orMolyvan 822 marketed by R.T. Vanderbilt Company or the productsSakura-lube 200, Sakura-lube 165, Sakura-lube 525 or Sakura-lube 600marketed by Adeka may be mentioned. In an embodiment of the invention,the content by weight of organomolybdenum compound ranges from 0.05 to3%, preferably from 0.1 to 2%, advantageously from 0.1 to 1% withrespect to the total weight of the lubricant composition.

Compound Comprising a Dithiophosphate Group

The lubricant composition according to the invention comprises at leastone compound comprising a dithiophosphate group. For the sake ofsimplicity of the description, the compound comprising a dithiophosphategroup is called “dithiophosphate” in the remainder of the presentdescription. The dithiophosphate, without being imitative, can beselected from the ammonium dithiophosphates, the amine dithiophosphates,the ester dithiophosphates and the metal dithiophosphates, alone or in amixture.

In an embodiment of the invention, the dithiophosphate is selected fromthe ammonium dithiophosphates of formula (IV):

in which R₇ and R₈ represent independently of one another an optionallysubstituted hydrocarbon-containing group, comprising from 1 to 30 carbonatoms.

In a preferred embodiment of the invention, R₇ and R₈ representindependently of one another an optionally substitutedhydrocarbon-containing group, comprising from 2 to 24 carbon atoms, morepreferentially from 3 to 18 carbon atoms, advantageously from 5 to 12carbon atoms. In another preferred embodiment of the invention, R₇ andR₈ represent independently of one another an unsubstitutedhydrocarbon-containing group, said hydrocarbon-containing group beingable to be an alkyl, alkenyl, alkynyl, phenyl or benzyl group. Inanother preferred embodiment of the invention, R₇ and R₈ representindependently of one another a linear or branched hydrocarbon-containingalkyl group, more preferentially a linear hydrocarbon-containing alkylgroup. In another preferred embodiment of the invention, R₇ and R₈represent independently of one another a hydrocarbon-containing groupoptionally substituted with at least one oxygen, nitrogen, sulphurand/or phosphorus atom, preferably with at least one oxygen atom.

As examples of ammonium dithiophosphate, the dimethyl ammoniumdithiophosphates, the diethyl ammonium dithiophosphates and the dibutylammonium dithiophosphates may be mentioned. In another embodiment of theinvention, the dithiophosphate is selected from the aminedithiophosphates of general formula (V):

-   -   in which:        -   R₉ and R₁₀ represent independently of one another a            hydrocarbon-containing group, optionally substituted,            comprising from 1 to 30 carbon atoms,        -   R₁₁, R₁₂ and R₁₃ represent independently of one another a            hydrogen atom or a hydrocarbon-containing group of 1 to 30            carbon atoms, it being understood that at least one of the            R₁₁, R₁₂ and R₁₃ groups does not represent a hydrogen atom.

In a preferred embodiment of the invention, R₉ and R₁₀ representindependently of one another a hydrocarbon-containing group, optionallysubstituted, comprising from 2 to 24 carbon atoms, more preferentiallyfrom 3 to 18 carbon atoms, advantageously from 5 to 12 carbon atoms. Inanother preferred embodiment of the invention, R₉ and R₁₀ representindependently of one another an unsubstituted hydrocarbon-containinggroup, said hydrocarbon-containing group being able to be an alkyl,alkenyl, alkynyl, phenyl or benzyl group. In another preferredembodiment of the invention, R₉ and R₁₀ represent independently of oneanother a linear or branched hydrocarbon-containing alkyl group, morepreferentially a linear hydrocarbon-containing alkyl group. In anotherpreferred embodiment of the invention, R₉ and R₁₀ representindependently of one another a hydrocarbon-containing group optionallysubstituted with at least one oxygen, nitrogen, sulphur and/orphosphorus atom, preferably with at least one oxygen atom. In anotherpreferred embodiment of the invention, R₁₁, R₁₂ and R₁₃ representindependently of one another a hydrocarbon-containing group comprisingfrom 2 to 24 carbon atoms, more preferentially from 3 to 18 carbonatoms, advantageously from 5 to 12 carbon atoms.

In another embodiment of the invention, the dithiophosphate is selectedfrom the ester dithiophosphates of general formula (VI):

-   -   in which:        -   R₁₄ and R₁₅ represent independently of one another a            hydrocarbon-containing group, optionally substituted,            comprising from 1 to 30 carbon atoms,        -   R₁₆ and R₁₇ represent independently of one another a            hydrocarbon-containing group comprising from 1 to 18 carbon            atoms.

In a preferred embodiment of the invention, R₁₄ and R₁₅ representindependently of one another an optionally substitutedhydrocarbon-containing group, comprising from 2 to 24 carbon atoms, morepreferentially from 3 to 18 carbon atoms, advantageously from 5 to 12carbon atoms. In another preferred embodiment of the invention, R₁₄ andR₁₅ represent independently of one another an unsubstitutedhydrocarbon-containing group, said hydrocarbon-containing group beingable to be an alkyl, alkenyl, alkynyl, phenyl or benzyl group. Inanother preferred embodiment of the invention, R₁₄ and R₁₅ representindependently of one another a linear or branched hydrocarbon-containingalkyl group, more preferentially a linear hydrocarbon-containing alkylgroup.

In another preferred embodiment of the invention, R₁₄ and R₁₅ representindependently of one another a hydrocarbon-containing group optionallysubstituted with at least one oxygen, nitrogen, sulphur and/orphosphorus atom, preferably with at least one oxygen atom. In anotherpreferred embodiment of the invention, R₁₄ and R₁₅ representindependently of one another, a hydrocarbon-containing group comprisingfrom 2 to 6 carbon atoms. In another preferred embodiment of theinvention, R₁₆ and R₁₇ represent independently of one another ahydrocarbon-containing group comprising from 2 to 6 carbon atoms.

In another embodiment, the dithiophosphate is selected from the metaldithiophosphates of general formula (VII):

-   -   in which:        -   R₁₈ and R₁₉ represent independently of one another an            optionally substituted hydrocarbon-containing group,            comprising from 1 to 30 carbon atoms,        -   M represents a metal cation, and        -   n is the valency of this metal cation.

In a preferred embodiment of the invention, the metal is selected fromthe group constituted by zinc, aluminium, copper, iron, mercury, silver,cadmium, tin, lead, antimony, bismuth, thallium, chromium, molybdenum,cobalt, nickel, tungsten, sodium, calcium, magnesium, manganese andarsenic. The preferred metals are zinc, molybdenum, antimony, preferablyzinc and molybdenum.* In a preferred embodiment of the invention, themetal is zinc. Mixtures of metals can be used. The metaldithiophosphates are neutral as exemplified in formula (VII) or basicwhen a stoichiometric excess of metal is present.

In a preferred embodiment of the invention, R₁₈ and R₁₉ representindependently of one another an optionally substitutedhydrocarbon-containing group, comprising from 2 to 24 carbon atoms, morepreferentially from 3 to 18 carbon atoms, advantageously from 5 to 12carbon atoms. In another preferred embodiment of the invention, R₁₈ andR₁₉ represent independently of one another an unsubstitutedhydrocarbon-containing group, said hydrocarbon-containing group beingable to be an alkyl, alkenyl, alkynyl, phenyl or benzyl group. Inanother preferred embodiment of the invention, R₁₈ and R₁₉ representindependently of one another a linear or branched hydrocarbon-containingalkyl group, more preferentially a linear hydrocarbon-containing alkylgroup. In another preferred embodiment of the invention, R₁₈ and R₁₉represent independently of one another a hydrocarbon-containing groupoptionally substituted with at least one oxygen, nitrogen, sulphurand/or phosphorus atom, preferably with at least one oxygen atom.

Advantageously, the dithiophosphate according to the invention is a zincdithiophosphate of formula (VII-a) or formula (VII-b):

in which R₁₈ and R₁₉ are as defined above.

As metal dithiophosphates according to the invention, Additin® RC 3038,Additin® RC 3045, Additin® RC 3048, Additin® RC 3058, Additin® RC 3080,Additin® RC 3180, Additin® RC 3212, Additin® RC 3580, Kikulube° Z112,Lubrizol® 1371, Lubrizol® 1375, Lubrizol® 1395, Lubrizol® 5179, Oloa®260, Oloa® 267 may for example be mentioned. In an embodiment of theinvention, the content by weight of dithiophosphate ranges from 0.1 to5%, preferably from 0.1 to 3%, advantageously from 0.5 to 2% withrespect to the total weight of the lubricant composition.

Fatty Triamine

The lubricant composition according to the invention comprises at leastone fatty triamine. The fatty triamines are mainly obtained fromcarboxylic acids. The starting fatty acids for obtaining fatty triaminesaccording to the invention can be selected from myristic, pentadecylic,palmitic, margaric, stearic, nonadecylic, arachidic, heneicosanoic,behenic, tricosanoic, lignoceric, pentacosanoic, cerotic, heptacosanoic,montanic, nonacosanoic, melissic, hentriacontanoic, laceroic acids orunsaturated fatty acids such as palmitoleic, oleic, erucic, nervonic,linoleic, a-linolenic, gamma-linolenic, di-homo-gamma-linolenic,arachidonic, eicosapentaenoic, docosahexaenoic acids.

The preferred fatty acids can originate from the hydrolysis of thetriglycerides present in vegetable or animal oils such as coconut, palm,olive, groundnut, rapeseed, sunflower, soya, cotton, linseed oil, beeftallow, etc. The natural oils may have been genetically modified so asto enrich their content of certain fatty acids. By way of example,rapeseed oil or oleic sunflower oil may be mentioned. In an embodimentof the invention, the fatty triamines can be obtained from naturalvegetable or animal resources.

In another embodiment of the invention, the fatty triamine is selectedfrom the compounds of formula (VIII):

R₂₀—N—[(CH₂)₃—NH₂]₂   (VII)

in which R₂₀ represents a linear or branched, saturated or unsaturatedalkyl group, comprising at least 10 carbon atoms, preferentially from 10to 22 carbon atoms, more preferentially from 14 to 22 carbon atoms,advantageously from 16 to 20 carbon atoms.

-   -   In a preferred embodiment of the invention, R₂₀ represents a        mixture of at least one saturated alkyl group comprising from 16        to 18 carbon atoms and a mono-unsaturated alkyl group comprising        from 16 to 18 carbon atoms.

In another embodiment of the invention, the fatty triamine is selectedfrom the compounds of formula (IX):

R₂₁—NH—(CH₂—CH₂—CH₂—NH)₂—H   (IX)

in which R₂₁ represents a linear or branched, saturated or unsaturatedalkyl group, comprising at least 10 carbon atoms, preferentially from 10to 22 carbon atoms, more preferentially from 14 to 22 carbon atoms,advantageously from 16 to 20 carbon atoms.

In an embodiment of the invention, the content by weight of fattytriamine ranges from 0.1 to 5%, preferably from 0.1 to 3%,advantageously from 0.5 to 2% with respect to the total weight of thecomposition. In another embodiment of the invention, the lubricantcomposition comprises a mass ratio (organomolybdenum compound/fattytriamine) ranging from 1/10 to 1, preferably from 1/5 to 4/5. In anotherembodiment of the invention, the lubricant composition comprises a massratio (organomolybdenum compound/compound comprising a dithiophosphategroup/fatty triamine) ranging from 1/10/10 to 1/1/1, preferably rangingfrom 1/5/5 to 4/5/5.

Base Oil

The lubricant compositions according to the invention can contain anytype of lubricant base oil, mineral, synthetic or natural, animal orvegetable, suitable for their use. The base oil or oils used in thelubricant compositions according to the present invention can be oils ofmineral or synthetic origin of groups I to V according to the classesdefined in the API classification (or their equivalents according to theATIEL classification) as summarized below, alone or in mixture.

TABLE I Saturates Sulphur Viscosity content content index (VI) Group IMineral oils  <90%  >0.03% 80 ≦ VI < 120 Group II Hydrocracked ≧90%≦0.03% 80 ≦ VI < 120 oils Group III Hydrocracked or ≧90% ≦0.03% ≧120hydro-isomerized oils Group IV Polyalphaolefins (PAO) Group V Esters andother bases not included in the bases of groups I to IV

The mineral base oils according to the invention include all types ofbases obtained by atmospheric and vacuum distillation of crude oil,followed by refining operations such as solvent extraction,deasphalting, solvent dewaxing, hydrotreatment, hydrocracking andhydroisomerization, hydrofinishing. The base oils of the compositionsaccording to the present invention can also be synthetic oils, such ascertain esters of carboxylic acids and of alcohols, or polyalphaolefins.The polyalphaolephins used as base oils are for example obtained frommonomers having from 4 to 32 carbon atoms (for example octene, decene),and a viscosity at 100° C. comprised between 1.5 and 15 cSt (measuredaccording to the standard ASTM D 445). Their average molecular weight istypically comprised between 250 and 3000 according to the standard ASTMD5296. Mixtures of synthetic and mineral oils can also be used.

There is no limitation as regards the use of one lubricant base oranother in order to produce the lubricant compositions according to theinvention, except that they must have properties, in particular ofviscosity, viscosity index, sulphur content, resistance to oxidation,suitable for use in a vehicle engine, preferentially a motor vehicleengine. In an embodiment of the invention, the lubricant bases representat least 50% by mass, with respect to the total mass of the lubricantcomposition, preferentially at least 60%, or also at least 70%.Typically, they represent between 75 and 99.9% by mass, with respect tothe total mass of the lubricant compositions according to the invention.

In a preferred embodiment of the invention, the lubricant compositionscomprise mineral bases of group I and/or III, or synthetic bases ofgroup IV according to the API classification. In another preferredembodiment of the invention, the lubricant compositions have a kinematicviscosity at 100° C. measured according to the standard ASTM D445ranging from 4 to 25 cSt, preferably from 5 to 22 cSt, advantageouslyfrom 5 to 13 cSt. In another preferred embodiment of the invention, thelubricant compositions have a viscosity index (VI) greater than or equalto 140, preferentially greater than or equal to 150, measured accordingto the standard ASTM 2270.

Other Additives

The lubricant compositions according to the invention can alsoadditionally contain at least one additive selected from the detergents,anti-wear additives different from a dithiophosphate, extreme pressureadditives, dispersants, pour-point improvers, anti-foaming agents,thickeners and mixtures thereof. In an embodiment, the lubricantcomposition can additionally comprise at least one antioxidant additive.The antioxidant additives slow down the degradation of the lubricantcompositions in service, in particular of the engine oils in service,degradation which can in particular result in the formation of deposits,the presence of sludges, or an increase in the viscosity of thelubricant composition, in particular of the engine oil. The antioxidantadditives act in particular as radical inhibitors or hydroperoxidedestroyers. Among the antioxidants commonly used, antioxidants of thephenolic or amine type, or phosphorus- and sulphur-containingantioxidants may be mentioned. Some of these antioxidants, for examplethe phosphorus- and sulphur-containing antioxidants, may generate ashes.The phenolic antioxidants may be ash-free, or be in the form of neutralor basic metal salts.

The antioxidant agents can be in particular selected from the stericallyhindered phenols, the esters of sterically hindered phenols and thesterically hindered phenols comprising a thioether bridge, thediphenylamines, the diphenylamines substituted with at least one C1-C12alkyl group, the N,N′ dialkyl aryl diamines and combinations thereof. Bysterically hindered phenol, is meant within the meaning of the presentinvention a compound comprising a phenol group in which at least onevicinal carbon of the carbon bearing the alcohol function is substitutedwith at least one C1-C10 alkyl group, preferably a C1-C6 alkyl group,preferably a C4 alkyl group, preferably with the tert-butyl group. Theamine compounds are another class of antioxidants which can be used,optionally in combination with the phenolic antioxidants. Typicalexamples are the aromatic amines of formula R₂₂R₂₃R₂₄N, in which R₂₂represents an aliphatic group or an optionally substituted aromaticgroup, R₂₃ represents an optionally substituted aromatic group, R₂₄represents a hydrogen atom, an alkyl group, an aryl group or a group offormula R₂₅S(O)_(z)R₂₆, where R₂₅ represents an alkylene group or analkenylene group, R2₆ represents an alkyl group, an alkenyl group or anaryl group and z represents an integer equal to 0, 1 or 2. Sulphurizedalkyl phenols or their alkali or alkaline-earth metal salts can also beused as antioxidants. Another class of antioxidants is that of thecopper compounds, for example the copper thio-or dithiophosphates, saltsof copper and of carboxylic acids, dithiocarbamates, sulphonates,phenates, copper acetylacetonates. Copper I and II salts of succinicacid or anhydride can also be used.

The lubricant composition according to the invention can contain anytype of antioxidant additives known to a person skilled in the art.Advantageously, the ash-free antioxidants are used. In an embodiment,the lubricant composition according to the invention can comprise from0.5 to 2% of at least one antioxidant additive by weight with respect tothe total mass of the lubricant composition.

In an embodiment, the lubricant composition according to the inventioncan also comprise a detergent additive. The detergent additives reducein particular the formation of deposits on the surface of the metalparts by dissolving the by-products of oxidation and combustion. Thedetergents that can be used in the lubricant composition according tothe invention are well known to a person skilled in the art. Thedetergents commonly used in the formulation of lubricant compositionscan be anionic compounds comprising a lipophilic longhydrocarbon-containing chain and a hydrophilic head. The associatedcation is typically a metal cation of an alkali or alkaline-earth metal.The detergents are preferentially selected from the alkali oralkaline-earth metal salts of carboxylic acids, sulphonates,salicylates, naphthenates, as well as the salts of phenates. The alkalior alkaline-earth metals are preferentially calcium, magnesium, sodiumor barium. These metal salts can contain the metal in an approximatelystoichiometric quantity or in excess (in a quantity greater than thestoichiometric quantity). In the latter case, these detergents arereferred to as overbased detergents. The excess metal providing thedetergent with its overbased character is present in the form of metalsalts which are insoluble in oil, for example carbonate, hydroxide,oxalate, acetate, glutamate, preferentially carbonate.

In an embodiment, the lubricant composition according to the inventioncan comprise from 2 to 4% by weight of detergent, with respect to thetotal mass of the lubricant composition. In an embodiment, the lubricantcomposition according to the invention can also comprise at least onepour point depressant additive. The pour point depressant additives inparticular improve the low-temperature behaviour of the lubricantcompositions, by slowing down the formation of paraffin crystals. Asexamples of pour point depressant additives, the alkylpolymethacrylates, polyacrylates, polyarylamides, polyalkylphenols,polyalkylnaphthalenes, alkylated polystyrenes may be mentioned.

In an embodiment, the lubricant composition according to the inventioncan also comprise at least one dispersant. The dispersants can beselected from the groups formed by the Mannich base or bases. In anembodiment, the lubricant composition according to the invention cancomprise from 0.2 to 10% by mass of dispersants with respect to thetotal mass of the lubricant composition.

In an embodiment, the lubricant composition can also comprise at leastone polymer improving the viscosity index. Among these polymers thepolymer esters, the ethylene and propylene copolymers, the homopolymersor copolymers of styrene, butadiene or isoprene, hydrogenated or not,and the polymethacrylates (PMA) may be mentioned. In an embodiment, thelubricant composition according to the invention can comprise from 1 to15% by mass of polymers improving the viscosity index, with respect tothe total mass of the lubricant composition.

In an embodiment of the invention, the lubricant composition comprises:

-   -   from 75 to 99.75% of at least one base oil,    -   from 0.05 to 3% of at least one organomolybdenum compound,    -   from 0.1 to 5% of at least one compound comprising a        dithiophosphate group,    -   from 0.1 to 5% of at least one fatty triamine.

In another embodiment of the invention, the lubricant compositioncomprises:

-   -   from 75 to 99.25% of at least one base oil,    -   from 0.05 to 3% of at least one organomolybdenum compound,    -   from 0.1 to 5% of at least one compound comprising a        dithiophosphate group,    -   from 0.1 to 5% of at least one fatty triamine,    -   from 0.5 to 5% of at least one other additive.

In another embodiment of the invention, the lubricant compositionessentially consists of:

-   -   75 to 99.75% of at least one base oil,    -   0.05 to 3% of at least one organomolybdenum compound,    -   0.1 to 5% of at least one compound comprising a dithiophosphate        group,    -   0.1 to 5% of at least one fatty triamine.

In another embodiment of the invention, the lubricant compositionessentially consists of:

-   -   75 to 99.25% of at least one base oil,    -   0.05 to 3% of at least one organomolybdenum compound,    -   0.1 to 5% of at least one compound comprising a dithiophosphate        group,    -   0.1 to 5% of at least one fatty triamine,    -   0.5 to 5% of at least one other additive.

All of the characteristics and preferences presented for the base oil,organomolybdenum compound, compound comprising a dithiophosphate group,the fatty triamine and the additional additive also apply to the abovelubricant compositions. In an embodiment of the invention, the lubricantcomposition is not an emulsion. In another embodiment of the invention,the lubricant composition is anhydrous. An object of the invention isalso an engine oil comprising a lubricant composition according to theinvention. All of the characteristics and preferences presented for thelubricant composition also apply to the engine oil according to theinvention.

In an embodiment of the invention, the engine oil can be of grades 0W-20and 5W-30 according to the SAE J300 classification, characterized by akinematic viscosity at 100° C. (KV100) ranging from 5.6 to 12.5 cStmeasured according to the international standard ASTM D445. In anotherembodiment of the invention, the engine oil can be characterized by aviscosity index, calculated according to the international standard ASTMD2230, greater than or equal to 130, preferably greater than or equal to150. In order to formulate an engine oil, base oils having a sulphurcontent less than 0.3%, for example mineral oils of group III, andsynthetic bases free of sulphur, preferentially of group IV, or mixturesthereof may advantageously be used.

An object of the invention is also the use of a lubricant composition asdefined above for the lubrication of mechanical parts, in particular intransmissions and/or vehicle engines, preferentially motor vehicleengines. An object of the invention is also the use of a lubricantcomposition as defined above for reducing friction between two steelsurfaces, in particular in a vehicle engine, preferentially a motorvehicle engine. An object of the invention is also the use of anabovementioned lubricant composition for reducing friction between asteel surface and a carbon-covered surface, in particular in a vehicleengine, preferentially a motor vehicle engine. An object of theinvention is also the use of a lubricant composition as defined abovefor reducing friction between two carbon-covered surfaces, in particularin a vehicle engine, preferentially a motor vehicle engine.

By carbon coating according to the invention, is meant any coatingcomprising carbon. These carbon coatings can be selected from diamondcoatings, and more particularly nanodiamond coatings. Such coatings canin particular be presented in the form of at least one nanocrystallinediamond layer, having a purity ranging from 70 to 99%.

In an embodiment of the invention, the carbon coatings are selected fromnanodiamond coatings in the form of at least one nanocrystalline diamondlayer having a purity ranging from 70 to 99%, preferentially rangingfrom 70 to 97%, advantageously of 75% and a thickness ranging from 0.1to 3μ, preferentially ranging from 0.5 to 2μ, advantageously of 1.5μ.These carbon coatings can also be selected from DLC (Diamond LikeCarbon) type coatings. Any type of DLC coating can be used as carboncoating according to the invention. The DLCs group together a set offamilies of amorphous materials essentially containing carbon.

Among these families, two families are mainly known and used: thehydrogenated DLCs, in particular the hydrogenated DLCs known as a-C:Hand the non-hydrogenated DLCs, in particular the non-hydrogenated DLCsknown as a-C or the non-hydrogenated DLCs known as to-C. The DLCs haveproperties which vary as a function of their sp3 hybrid carbon contentand their hydrogen content. Certain variants of DLC can be doped withmetal elements, such as iron, chromium or tungsten.

Compared with diamond coatings, the DLC coatings are generally lessmechanically and thermally resistant as these are amorphous materials.However, they are generally less rough and above all can be applied tothe majority of substrates at a low temperature. In an embodiment of theinvention, the DLCs are selected from the hydrogenated DLCs, inparticular the hydrogenated DLCs known as a-C:H. In a preferredembodiment of the invention, the DLCs are selected from the hydrogenatedDLCs, in particular the hydrogenated DLCs known as a-C:H containing from10 to 40% of hydrogen.

The above use also makes it possible to not worsen, or even to reducethe wear between two steel surfaces, in particular in a vehicle engine,preferentially a motor vehicle engine. The above use also makes itpossible to not worsen, or even to reduce the wear between a steelsurface and a carbon-covered surface, in particular in a vehicle engine,preferentially a motor vehicle engine. The above use also makes itpossible to not worsen, or even to reduce the wear between twocarbon-covered surfaces, in particular in a vehicle engine,preferentially a motor vehicle engine.

The invention also relates to the use of a lubricant composition asdefined above for reducing the fuel consumption of vehicles,preferentially of motor vehicles. All of the characteristics andpreferences presented for the lubricant composition also apply to theabove uses. The invention also relates to a process for the lubricationof mechanical parts, in particular in transmissions and/or vehicleengines, preferentially motor vehicle engines, comprising at least onestep of bringing at least one part into contact with a lubricantcomposition as defined above.

An object of the invention is also a process for reducing frictionbetween two steel surfaces, in particular in a vehicle engine,preferentially a motor vehicle engine, comprising at least one step ofbringing at least one of the steel surfaces into contact with alubricant composition as defined above. An object of the invention isalso a process for reducing friction between a steel surface and acarbon-covered surface, in particular in a vehicle engine,preferentially a motor vehicle engine, comprising at least one step ofbringing at least one of the surfaces into contact with a lubricantcomposition as defined above. An object of the invention is also aprocess for reducing friction between two carbon-covered surfaces, inparticular in a vehicle engine, preferentially a motor vehicle engine,comprising at least one step of bringing at least one of thecarbon-covered surfaces into contact with a lubricant composition asdefined above.

The above process also makes it possible to not worsen, or even toreduce the wear between two steel surfaces, in particular in a vehicleengine, preferentially a motor vehicle engine. The above process alsomakes it possible to not worsen, or even to reduce the wear between asteel surface and a carbon-covered surface, in particular in a vehicleengine, preferentially a motor vehicle engine. The above process alsomakes it possible to not worsen, or even to reduce the wear between twocarbon-covered surfaces, in particular in a vehicle engine,preferentially a motor vehicle engine.

An object of the invention is also a process for reducing the fuelconsumption of a vehicle, preferentially of a motor vehicle, comprisingat least one step of bringing a mechanical part of the vehicle engineinto contact with a lubricant composition as defined above. All of thecharacteristics and preferences presented for the lubricant compositionalso apply to the above processes. The vehicles can comprise a two orfour stroke internal combustion engine.

The engines can be gasoline engines or diesel engines intended to besupplied with standard gasoline or diesel. By “standard gasoline” or by“standard diesel”, is meant within the meaning of the present invention,engines which are supplied with a fuel obtained after refining of an oilof mineral origin (such as petroleum for example). The engines can alsobe gasoline engines or diesel engines modified to be supplied with afuel based on oils originating from renewable materials such as fuelsbased on alcohol or biodiesel fuel. The vehicles can be light vehiclessuch as cars and motorcycles. The vehicles can also be heavy goodsvehicles, public works vehicles and ships.

An object of the invention is also the use of a fatty triamine in alubricant composition comprising at least one base oil, at least oneorganomolybdenum compound and at least one compound comprising adithiophosphate group for reducing friction between two steel surfaces,in particular in a vehicle engine, preferentially a motor vehicleengine. An object of the invention is also the use of a fatty triaminein a lubricant composition comprising at least one base oil, at leastone organomolybdenum compound and at least one compound comprising adithiophosphate group for reducing friction between a steel surface anda carbon-covered surface, in particular in a vehicle engine,preferentially a motor vehicle engine. An object of the invention isalso the use of a fatty triamine in a lubricant composition comprisingat least one base oil, at least one organomolybdenum compound and atleast one compound comprising a dithiophosphate group for reducingfriction between two carbon-covered surfaces, in particular in a vehicleengine, preferentially a motor vehicle engine.

The above use also makes it possible to not worsen, or even to reducethe wear between two steel surfaces, in particular in a vehicle engine,preferentially a motor vehicle engine. The above use also makes itpossible to not worsen, or even to reduce the wear between a steelsurface and a carbon-covered surface, in particular in a vehicle engine,preferentially a motor vehicle engine. The above use also makes itpossible to not worsen, or even to reduce the wear between twocarbon-covered surfaces, in particular in a vehicle engine,preferentially a motor vehicle engine.

An object of the invention is also the use of a fatty triamine in alubricant composition comprising at least one base oil, at least oneorganomolybdenum compound and at least one compound comprising adithiophosphate group for reducing the fuel consumption of a vehicle,preferentially of a motor vehicle. All of the characteristics andpreferences presented for the base oil, the fatty triamine, theorganomolybdenum compound and the compound comprising a dithiophosphategroup also apply to the above uses.

The invention also relates to a composition of the additives concentratetype comprising:

-   at least one organomolybdenum compound,-   at least one compound comprising a dithiophosphate group, and-   at least one fatty triamine.

All of the characteristics and preferences presented for the fattytriamine, the organomolybdenum compound and the compound comprising adithiophosphate group also apply to the composition of theabovementioned additives concentrate type. In an embodiment of theinvention, the composition of the additives concentrate type alsocomprises at least one additional additive. The additional additive canbe selected from the abovementioned additives. In an embodiment of theinvention, at least one base oil can be added to the composition of theadditives concentrate type according to the invention, in order toobtain a lubricant composition according to the invention.

The different objects of the present invention and their implementationswill be better understood on reading the following examples. Theseexamples are given as an indication, non limitatively.

EXAMPLES Example 1

Lubricant compositions No. 1 to No. 6 are prepared from the followingcompounds:

-   a base oil of group Ill having a viscosity at 100° C. of 4.3 cSt    measured according to the standard ASTM D445,-   a compound comprising a dithiophosphate group: zinc dithiophosphate    (Lz 1371 marketed by Lubrizol),-   an organomolybdenum compound 1: organomolybdenum complex of formula    (l-a) in which R₁ represents a hydrocarbon group comprising 11    carbon atoms (Molyvan 855 marketed by Vanderbilt company),-   an organomolybdenum compound 2: molybdenum dithiocarbamate    (Sakura-lube 525 marketed by Adeka company),-   a fatty triamine of formula (VIII) in which R₂₀ represents a    hydrocarbon group comprising from 16 to 18 carbon atoms (Triameen YT    marketed by AKZO). Lubricant compositions No. 1 to No. 6 are    described in Table II; the percentages given are percentages by    mass.

TABLE II Lubricant composition No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 Baseoil 100 98.5 98.6 97.5 97.6 99 Compound 1 1 1 1 comprising adithiophosphate group Organomolybdenum 0.5 0.5 compound 1Organomolybdenum 0.4 0.4 compound 2 Fatty triamine 1 1 1

Test 1: Assessment of the Friction Properties of Lubricant Compositionson a Steel/Steel Ccontact

The friction properties of lubricant compositions No. 1, No. 2 and No. 4on steel/steel contacts are assessed by measurement of the coefficientof friction. The coefficient of friction is assessed using aball-on-flat linear tribometer under the following conditions:

-   grade of the steel: 100c6-   temperature: 80° C.,-   normal load of 5N,-   travel of 5 mm.    A difference of at least 0.01 between two coefficient of friction    values is considered as significant for showing the influence on    said coefficient of friction. Table Ill shows the coefficient of    friction of lubricant compositions No. 1, No. 2 and No. 4.

TABLE III Composition No. 1 No. 2 No. 4 Coefficient of 0.150 0.035 0.025friction steel/steel

These results show that lubricant composition according to the inventionNo. 4 has improved friction properties for steel/steel contacts,relative to a lubricant composition comprising an organomolybdenumcompound according to the invention and a compound comprising adithiophosphate group according to the invention but comprising no fattytriamine according to the invention (composition No. 2). In addition tothese results relating to the coefficient of friction, it was observedthat the wear to the surface of the balls is not worsened by the use oflubricant composition according to the invention No. 4, in comparisonwith lubricant composition No. 2.

Test 2: Assessment of the Friction Properties of Lubricant Compositionson a DLC/Steel Contact

The friction properties of lubricant compositions No. 1, No. 2, No. 4and No. 6 on the DLC/steel contacts are assessed by measurement of thecoefficient of friction. The coefficient of friction is assessed using aDLC ball/steel flat linear tribometer under the following conditions:

-   grade of the steel: 100c6,-   nature of the DLC coating of the balls: hydrogenated DLC a:CH    containing between 31 and 33% of hydrogen and having a molar ratio    (sp² carbon/sp³ carbon) equal to 55/45,-   thickness of the DLC layer: 1.5μ,-   temperature: 110° C.,-   normal load of 5 N,-   travel of 10 mm.    A difference of at least 0.01 between two coefficient of friction    values is considered as significant for showing the influence on    said coefficient of friction.-   Table IV shows the coefficient of friction of lubricant compositions    No. 1, No. 2, No. 4 and No. 6.

TABLE IV Composition No. 1 No. 2 No. 4 No. 6 Coefficient of 0.070 0.0700.053 0.080 friction DLC/steel

These results show that lubricant composition according to the inventionNo. 4 has improved friction properties on DLC/steel contacts, incomparison with a lubricant composition comprising an organomolybdenumcompound according to the invention and a compound comprising adithiophosphate group according to the invention but comprising no fattytriamine according to the invention (composition No. 2), as well as incomparison with a lubricant composition comprising a fatty triamineaccording to the invention but comprising no organomolybdenum compoundaccording to the invention and no compound comprising a dithiophosphategroup according to the invention (composition No. 6). It is of interestto note that the coefficient of frictions of lubricant compositions No.2 and No. 6 are higher than the coefficient of friction of lubricantcomposition according to the invention No. 4, thus demonstrating asynergistic effect of the combination of an organomolybdenum compoundaccording to the invention, a compound comprising a dithiophosphategroup according to the invention and a fatty triamine according to theinvention, for reducing friction on DLC/steel contacts. In conjunctionwith these results relating to the coefficient of friction, it has beenobserved that the wear of the DLC coating of the balls is not worsenedby the use of lubricant composition according to the invention No. 4, incomparison with lubricant compositions No. 2 and No. 6.

Test 3: Assessment of the Friction Properties of Lubricant Compositionson a DLC/Steel Contact

The friction properties of lubricant compositions No. 1, No. 2 and No. 4on DLC/steel contacts are assessed by measurement of the coefficient offriction. The coefficient of friction is assessed using a DLC ball/steelflat HFFR tribometer under the following conditions:

-   grade of the steel: 100c6-   nature of the DLC coating: hydrogenated DLC a:CH containing between    31 and 33% of hydrogen and having a molar ratio (sp²    carbon/sp³carbon) equal to 55/45,-   thickness of the DLC layer: 1.5μ,-   temperature: 110° C.,-   frequency: 20 Hz.    A difference of at least 0.01 between two coefficient of friction    values is considered as significant for showing the influence on    said coefficient of friction. Table V shows the coefficient of    friction of lubricant compositions No. 1, No. 2 and No. 4.

TABLE V Composition No. 1 No. 2 No. 4 Coefficient of 0.070 0.090 0.060friction DLC/steel

These results confirm the results of test 2; in fact, they demonstratethat the lubricant composition according to the invention No. 4 hasimproved friction properties for DLC/steel contacts, relative to alubricant composition comprising an organomolybdenum compound accordingto the invention and a compound comprising a dithiophosphate groupaccording to the invention but comprising no fatty triamine according tothe invention (composition No. 2).

Test 4: Assessment of the Friction Properties of Lubricant Compositionson a DLC/Steel Contact

The friction properties of lubricant compositions No. 1, No. 3 and No. 5on the DLC/steel contacts are assessed by measurement of the coefficientof friction. The coefficient of friction is assessed according to themethod described in test 3. A difference of at least 0.01 between twocoefficient of friction values is considered as significant for showingthe influence on said coefficient of friction. Table VI shows thecoefficient of friction of lubricant compositions No. 1, No. 3 and No.5.

TABLE VI Composition No. 1 No. 3 No. 5 Coefficient of 0.070 0.090 0.060friction DLC/steel

These results confirm the results of test 2 and test 3; in fact, theydemonstrate that the lubricant composition according to the inventionNo. 5 has improved friction properties for DLC/steel contacts, relativeto a lubricant composition comprising an organomolybdenum compoundaccording to the invention and a compound comprising a dithiophosphategroup according to the invention but comprising no fatty triamineaccording to the invention (composition No. 3), in the presence of anorganomolybdenum compound 2 that is different from organomolybdenumcompound 1.

Example 2

Lubricant compositions No. 7 to No. 10 are prepared from the followingcompounds:

-   a polyalphaolefin type oil of having a viscosity at 100° C. of 4 cSt    measured according to the standard ASTM D445,-   a compound comprising a dithiophosphate group: zinc dithiophosphate    (Lz 1371 marketed by Lubrizol company),-   an organomolybdenum compound 1: organomolybdenum complex of formula    (l-a) in which R₁ represents a hydrocarbon group comprising 11    carbon atoms (Molyvan 855 marketed by Vanderbilt company),-   a fatty triamine of formula (VIII) in which R₂₀ represents a    hydrocarbon group comprising from 16 to 18 carbon atoms (Triameen YT    marketed by AKZO). Lubricant compositions No. 7 to No. 10 are    described in Table VII; the percentages given are percentages by    mass.

TABLE VII Lubricant composition No. 7 No. 8 No. 9 No. 10 Base oil 10098.5 97.5 99 Compound 1 1 comprising a dithiophosphate groupOrganomolybdenum 0.5 0.5 compound 1 Fatty triamine 1 1

Test 5: Assessment of the Friction Properties of Lubricant Compositionson a Steel/Steel Contact

The friction properties of lubricant compositions No. 7, No. 8, No. 9and No. 10 on steel/steel contacts are assessed by measurement of thecoefficient of friction. The coefficient of friction is assessedaccording to the method described in test 1. A difference of at least0.01 between two coefficient of friction values is considered assignificant for showing the influence on said coefficient of friction.Table VIII shows the coefficient of friction of lubricant compositionsNo. 7, No. 8, No. 9 and No. 10.

TABLE VIII Composition No. 7 No. 8 No. 9 No. 10 Coefficient of 0.1400.050 0.035 0.120 friction steel/steel

These results show that lubricant composition according to the inventionNo. 9 has improved friction properties on steel/steel contacts, incomparison with a lubricant composition comprising an organomolybdenumcompound according to the invention and a compound comprising adithiophosphate group according to the invention but comprising no fattytriamine according to the invention (composition No. 8), as well as incomparison with a lubricant composition comprising a fatty triamineaccording to the invention but comprising no organomolybdenum compoundaccording to the invention and no compound comprising a dithiophosphategroup according to the invention (composition No. 10). It is of interestto note that the coefficients of friction of lubricant compositions No.8 and No. 10 are higher than the coefficient of friction of lubricantcomposition according to the invention No. 9, thus demonstrating asynergistic effect of the combination of an organomolybdenum compoundaccording to the invention, a compound comprising a dithiophosphategroup according to the invention and a fatty triamine according to theinvention for reducing friction on steel/steel contacts. In addition tothese results relating to the coefficient of friction, it has beenobserved that the wear to the surface of the balls is not worsened bythe use of the lubricant composition according to the invention No. 9,in comparison with the lubricant compositions No. 8 and 10.

Test 6: Assessment of the Friction Properties of Lubricant Compositionson a Steel/Diamond Contact

The friction properties of lubricant compositions No. 7, No. 8 and No. 9on steel/diamond contacts are assessed by measurement of the coefficientof friction. The coefficient of friction is assessed using a nanodiamondball/steel flat linear tribometer under the following conditions:

-   grade of the steel: 100c6,-   nature of the nanodiamond coating: nanocrystalline diamond layer    comprising approximately 75% of sp³ hybrid carbon atoms (purity of    approximately 75%), of thickness equal to 1.5μ, surface roughness    equal to 14 nm, hardness of approximately 74 GPa and having a    Young's modulus equal to 620 GPa,-   temperature: 80° C.,-   normal load of 10 N,-   travel of 5 mm.-   A difference of at least 0.01 between two coefficient of friction    mass values is considered as significant for showing the influence    on said coefficient of friction. Table IX shows the coefficient of    friction of lubricant compositions No. 7, No. 8 and No. 9.

TABLE IX Composition No. 7 No. 8 No. 9 Coefficient of 0.110 0.070 0.060friction steel/diamond

These results show that the lubricant composition according to theinvention No. 9 has improved friction properties for steel/diamondcontacts, relative to a lubricant composition comprising anorganomolybdenum compound according to the invention and a compoundcomprising a dithiophosphate group according to the invention butcomprising no fatty triamine according to the invention (composition No.8). In addition to these results relating to the coefficient offriction, it has been observed that the wear of the nanodiamond coatingof the balls is not worsened by the use of the lubricant compositionaccording to the invention No. 9, in comparison with the lubricantcomposition No. 8.

Test 7: Assessment of the Friction Properties of Lubricant Compositionson a DLC/Steel Contact

The friction properties of lubricant compositions No. 7, No. 8 and No. 9on DLC/steel contacts are assessed by measurement of the coefficient offriction. The coefficient of friction is assessed according to themethod described in test 2. A difference of at least 0.01 between twocoefficient of friction values is considered as significant for showingthe influence on said coefficient of friction. Table X shows thecoefficient of friction of lubricant compositions No. 7, No. 8 and No.9.

TABLE X Composition No. 7 No. 8 No. 9 Coefficient of 0.070 0.080 0.070friction steel/diamond

These results show that the lubricant composition according to theinvention No. 9 has improved friction properties for DLC/steel contacts,relative to a lubricant composition comprising an organomolybdenumcompound according to the invention and a compound comprising adithiophosphate group according to the invention but comprising no fattytriamine according to the invention (composition No. 8).

Thus, all of the above examples and tests demonstrate that the presenceof a combination of an organomolybdenum compound according to theinvention, a compound comprising a dithiophosphate group according tothe invention and a fatty triamine according to the invention in alubricant composition makes it possible to give this compositionfriction properties that are equivalent, or even improved both onsteel/steel contacts and on steel/carbon coating contacts, in particularon steel/nanodiamond contacts but also steel/DLC contacts. The presenceof such a combination in a lubricant composition also allows thelubricant composition to retain good anti-wear properties, both onsteel/steel contacts and on steel/carbon coating contacts, in particularon steel/nanodiamond contacts but also on steel/DLC contacts.

1. A lubricant composition comprising: at least one base oil, at leastone organomolybdenum compound, at least one compound comprising adithiophosphate group, and at least one fatty triamine.
 2. The lubricantcomposition according to claim 1 in which the organomolybdenum compoundis a molybdenum dithiocarbamate compound.
 3. The lubricant compositionaccording to claim 1 in which the organomolybdenum compound is amolybdenum complex comprising at least one compound selected from: (a)the compounds of formula (I)

in which: X¹represents an oxygen atom or a nitrogen atom; X² representsan oxygen atom or a nitrogen atom; n represents 1 when X¹ represents anoxygen atom and m represents 1 when X² represents an oxygen atom; nrepresents 2 when X¹ represents a nitrogen atom and m represents 2 whenX² represents a nitrogen atom; R₁ represents a linear or branched,saturated or unsaturated alkyl group, comprising from 3 to 30 carbonatoms; the compounds of formula (II)

in which: X¹ represents an oxygen atom or a nitrogen atom; X² representsan oxygen atom or a nitrogen atom; n represents 1 when X¹ represents anoxygen atom and m represents 1 when X² represents an oxygen atom; nrepresents 2 when X¹ represents a nitrogen atom and m represents 2 whenX² represents a nitrogen atom; R₁ represents a linear or branched,saturated or unsaturated alkyl group, comprising from 3 to 30 carbonatoms; R₂ represents a linear or branched, saturated or unsaturatedalkyl group, comprising from 3 to 30 carbon atoms; and (b) a mixture ofat least one compound of formula (I) and at least one compound offormula (II).
 4. The lubricant composition according to claim 3 in whichthe molybdenum complex comprises at least one compound of formula (I-a)

in which R₁ represents a linear or branched, saturated or unsaturatedalkyl group, comprising from 3 to 30 carbon atoms.
 5. The lubricantcomposition according to claim 3 in which the molybdenum complexcomprises at least one compound of formula (II-a)

in which R₁ represents a linear or branched, saturated or unsaturatedalkyl group, comprising from 3 to 30 carbon atoms.
 6. The lubricantcomposition according to claim 1 in which the content by weight oforganomolybdenum compound ranges from 0.05 to 3% with respect to thetotal weight of the lubricant composition.
 7. The lubricant compositionclaim 1 in which the compound comprising a dithiophosphate group isselected from the group constituted by the ammonium dithiophosphates,amine dithiophosphates, ester dithiophosphates and metaldithiophosphates, alone or in a mixture.
 8. The lubricant compositionaccording to claim 1 in which the compound comprising a dithiophosphategroup is a compound of formula (VII)

in which: R₁₈ represents a linear or branched, saturated or unsaturated,substituted or unsubstituted alkyl group, comprising from 1 to 30 carbonatoms; R₁₉ represents a linear or branched, saturated or unsaturated,substituted or unsubstituted alkyl group, comprising from 1 to 30 carbonatoms; M represents a metal cation, preferably a Zn²⁺cation; and nrepresents the valency of the metal cation.
 9. The lubricant compositionaccording to any claim 1 in which the compound comprising adithiophosphate group is a compound of formula (VII-a) or formula(VII-b):

in which: R₁₈ represents a linear or branched, saturated or unsaturated,substituted or unsubstituted alkyl group, comprising from 1 to 30 carbonatoms; and R₁₉ represents a linear or branched, saturated orunsaturated, substituted or unsubstituted alkyl group, comprising from 1to 30 carbon atoms.
 10. The lubricant composition according to any claim1 in which the content by weight of compound comprising adithiophosphate group ranges from 0.1 to 5% with respect to the totalweight of the lubricant composition.
 11. The lubricant compositionaccording to claim 1 in which the fatty triamine is selected from: thecompounds of formula (VIII)R₂₀—N—[(CH₂)₃—NH₂]₂   (VIII) in which R₂₀ represents a linear orbranched, saturated or unsaturated alkyl group, comprising at least 10carbon atoms; and the compounds of formula (IX)R₂₁—NH—(CH₂—CH₂—CH₂—NH)₂—H   (IX) in which R₂₁ represents a linear orbranched, saturated or unsaturated alkyl group, comprising at least 10carbon atoms.
 12. The lubricant composition according to claim 1 inwhich the content by weight of fatty triamine ranges from 0.1 to 5% withrespect to the total weight of the lubricant composition.
 13. Thelubricant composition according to claim 1 in which the mass ratio(organomolybdenum compound/fatty triamine) ranges from 1/10 to 1
 14. Thelubricant composition according to claim 1 in which the mass ratio(organomolybdenum compound/compound comprising a dithiophosphategroup/fatty triamine) ranges from 1/10/10 to 1/1/1.
 15. The lubricantcomposition according to claim 1 further comprising at least oneadditive selected from the detergents, anti-wear additives differentfrom ammonium dithiophosphates, amine dithiophosphates, esterdithiophosphates and metal dithiophosphates, extreme pressure additives,dispersants, pour-point improvers, anti-foaming agents, thickeners andmixtures thereof.
 16. A method comprising reducing friction between twosteel surfaces, between two carbon-covered surfaces or between a steelsurface and a carbon-covered surface in a vehicle engine, the methodfurther comprising bringing the surfaces into contact with a lubricantcomposition comprising: at least one base oil, at least oneorganomolybdenum compound, at least one compound comprising adithiophosphate group, and at least one fatty triamine. 17-18.(canceled)
 19. A method comprising bringing a mechanical part of avehicle engine into contact with a lubricant composition, and reducingfuel consumption of vehicles, the lubricant composition comprising: atleast one base oil, at least one organomolybdenum compound, at least onecompound comprising a dithiophosphate group, and at least one fattytriamine.
 20. A composition of additives concentrate comprising: atleast one organomolybdenum compound, at least one compound comprising adithiophosphate group, and at least one fatty triamine.